The invention relates to an improved heat exchanger and an integrated blood heat exchanger and oxygenator and methods of making and using the same, and more specifically to a device which is compact and provides for improved oxygenation and heat exchange.
Various forms of blood oxygenators and heat exchangers are known in the prior art. Blood oxygenators and heat exchangers are commonly used during open heart surgery and are coupled to a cardiopulmonary bypass circuit to take over the function of the heart and lungs. The heat exchanger portion is typically used to cool the blood and lower the body temperature during open heart surgery. Reducing body temperature significantly reduces the demand for oxygen by various vital organs. Near the end of the surgery, the blood is heated to raise the body temperature.
During oxygenation, oxygen gas supplies oxygen to the blood and, in some oxygenators, releases CO.sub.2. Two common types of oxygenators are bubble oxygenators and membrane oxygenators. With bubble oxygenators, gas bubbles containing oxygen are introduced directly into the blood. Usually, a defoamer is employed to remove gas bubbles from the blood following bubble oxygenation. Examples of bubble oxygenators are disclosed in U.S. Pat. Nos. 4,374,088 and 4,637,917. With membrane oxygenators, oxygen passes along one side of a permeable membrane and blood along the other. The permeable membrane has a sufficient pore size such that oxygen molecules pass through the membrane to be diffused into the blood as dissolved oxygen. However, the pores are sufficiently small such that blood cannot flow to the oxygen side. An example of the use of a microporous membrane sheet to oxygenate blood where blood flows along one side of a membrane sheet and oxygen along the other is disclosed in U.S. Pat. Nos. 4,451,562 and 4,424,190. Bundles of hollow fiber membrane tubes may also be used, where oxygen passes through the hollows of the tubes and blood flows along the outside of the tubes. Hollow tube membrane oxygenators are disclosed in U.S. Pat. Nos. 4,948,560, Re. 33,932, and 4,639,353.